import java.util.Arrays;
import java.util.function.DoubleToIntFunction;

public class Day729 {
    public static void main(String[] args) {
        
    }











    public static String myToString(int[] array) {
        if (array == null){
            return "null";
        }
        String str = "[";
        for (int i = 0; i < array.length; i++){
            str = str + array[i];
            if (i != array.length-1){
                str = str + ",";
            }
        }
        str = str + "]";
        return str;
    }
    public static void main2(String[] args) {
        //int[] array = {1,2,3};
        //int[] array = null;
        int[] array = {};
        System.out.println(myToString(array));
    }







    /*public static void Transform(int[] array) {
        for (int i = 0; i < array.length; i++){
            array[i] = 2*array[i];
        }
    }*/
    public static int[]  Transform1(int[] array) {
        int[] ret = new int[array.length];
        for (int i = 0; i < array.length; i++){
            ret[i] = 2*array[i];
        }
        return ret;
    }
    public static void main1(String[] args) {
        int[] array = {1,2,3};
        //Transform(array);
        //System.out.println(Arrays.toString(array));
        int[] ret1 = Transform1(array);
        System.out.println(Arrays.toString(array));
        System.out.println(Arrays.toString(ret1));
    }

}
